In sales, immediate communication with your prospects and current customers is important. Being available to answer questions or further negotiate a deal allows your clients to feel secure and more apt to purchase from you. But what if you can’t answer the phone when they call? Make sure you have a voicemail system set up so your clients have the opportunity to leave you a message.
If you have a call forwarding set up, it is likely to cause conflicts with voicemail. To turn off Call Forwarding or make sure it is not enabled:

I can access my voicemail from my phone just fine. I’m just cheap and used Hangout/Google Voice to save my minutes.
2. Enter the destination you wish to transfer the call to, then press [SEND] softkey. 3. Once the receiving party answers, announce the call. 4. To complete the transfer, press again. If you hang up before the call rings, the transfer will fail and the call will be disconnected. Direct to Voicemail: Transfer a call directly to voicemail 1. Press . 2. If a phone rings once and then goes to voicemail or rings only briefly, it You can't definitively know the cause of a phone barely ringing and going to voicemail because neither a phone company nor the phone's operating system provider will tell you if your phone number is blocked.